Development of Measurement Instruments for Space-Time Density Distribution of Floating Small Particles

为了研制漂浮小颗粒尺寸和密度的测量仪器，本研究研究了以下三种方法用激光束扫描法测量小颗粒的方法该方法是通过检测小颗粒在照射下通过激光束的光散射，得到随时间变化的随机脉冲信号的振幅直方图，从而导出颗粒密度和粒度谱。具体研究内容包括：(1)激光扫描光学系统和检测系统的优化设计、构建和改进；(2)散射光时积分强度的空间分布显示方法、粒子大小和密度分析；(3)可能测量粒子的评价和仪器的总体评价。在这些结果的基础上，一个测量仪器实际上被建造了利用运动透射光栅的小颗粒光学测量方法这种方法称为空间滤波测速法，它是利用光电探测器探测通过透射光栅的运动小颗粒的光学图像，并通过分析电信号的频率分布来确定颗粒的速度、大小和密度。具体研究内容包括：(1)方法原理与理论；(2)利用两个旋转透射光栅测量二维速度；(3)图像光纤在空间滤波测速中的应用；(4)空间滤波测速中粒子密度与尺寸的测量。在这些结果的基础上，研制和制造了几种测速仪该方法基于双曝光散斑摄影技术，测量粉末床同一表面在两种不同激光照射下产生的两种散斑图案之间的相关程度。进行了初步研究，以验证该方法的有效性，并显示其在在线测量过程中使用的可能性。少

For the purpose of developing measurement instruments for the size and density of floating small particles, the present study investigates the following three methods.[1] Measurement method of small particles using a laser-beam scanning method The method is to derive the particle density and the particle-size spectra from the amplitude histogram of time-dependent random pulse signals obtained by detecting the light scattering from the small particles passing through the laser beam under illumination. Actual studies were performed in the following items: (1) optimum designs of the laser-beam scanning optical system and the detecting system, and their construction and improvement, (2) display method for the spatial distribution of time-integrated intensity of the scattering light, and analysis of the particle size and density, and (3) evaluation of passibly measuring particles and overall evaluation of the instrument. On the basis of these results, a measurement instrument was actually c … More onstructed.[2] Optical measurement method of small particles using moving transmission gratings The method, which is called spatial filtering velocimetry, is to detect, by means of a photodetector, the optical images of moving small particles through a transmission grating and to determine the velocity, size and density of particles by analyzing the frequency distribution of electric signals. Actual studies were conducted in the following items: (1) principle and theory of the methods, (2) measurements of the two-dimensional velocity using two rotating transmission gratings, (3) application of an image fiber to spatial filtering velocimetry, and (4) measurements of the particle density and size in spatial filtering velocimetry. On the basis of these results, several velocimeters were developed and constructed.[3] Measurement method of fine particle size using a speckle correlation technique The method is based on double-exposure speckle photography and is to measure the degree of correlation between the two speckle patterns produced from the same surface of a powder bed under two different laser illuminations. A preliminary study was performed to verify the usefulness of the method and to show the possibility of its use in an on-line measuring process. Less